1. Field of the Invention
The invention relates generally to a liquid delivery system (LDS). More particularly, it relates to a liquid delivery system capable of not only improving the deposition speed of copper but also implementing a high reproduction, when forming a copper wire using chemical vapor deposition method during the process of manufacturing a semiconductor device.
2. Description of the Prior Art
Generally, as the degree of integration and performance of a semiconductor device becomes higher, copper metal wire has been widely used as a metal wire in a semiconductor device. In the copper metal wire, the metal layer is deposited through physical vapor deposition (PVD) method, metal-organic chemical vapor deposition (MOCVD) method, electrical plating method etc. A conventional liquid delivery apparatus used to deposit copper through chemical vapor deposition method may include bubbler and direct liquid injection (DLI) apparatus.
As can be seen from FIG. 1, a conventional bubbler 10 comprises an inlet line 11, a canister 12 and an outlet line 14. A carrier gas is introduced via the inlet line 11. The introduced gas is mixed at a given ratio with metal liquid materials 13 contained in the canister 12 of the bubbler 10. The mixed gas then exits the canister 12 via the outlet line 14. The mixing ratio of the carrier gas with the metal liquid materials depends on the mass flow of the carrier gas, the temperature of the bubbler 10 and the pressure of the bubbler 10. This conventional type of bubbler 10 is not suitable for liquid materials such as copper liquid materials having a very low steam pressure. More particularly, it is required that the temperature of the bubbler 10 is kept constant. This makes the copper liquid materials likely to decompose, so that particles are generated. Accordingly, the conventional bubbler 10 has problems that it not only adversely affects the deposition film but also degrades reproduction and has a very low deposition speed.
FIG. 2 is a schematic view of a direct liquid injection (DLI) apparatus 230 currently used for deposition of copper through a metal-organic chemical vapor deposition method.
The DLI apparatus 230 principally comprises a micropump 20 and a vaporizer 30. The DLI apparatus pressurizes metal liquid materials from the ampule 19 at a pressure of about 20 psi and then passes them to the micropump 20 via the first valve 21. As the first piston 23 is raised by the first stepping motor 22, the metal liquid materials fill the first cylinder 24. Then the first valve 21 is closed and the second valve 25 is opened. Next, the first piston 23 is lowered while the second piston 27 is raised by the second stepping motor 26, causing the metal liquid materials filled in the first cylinder 24 [will] to flow into the second cylinder 28 via the second valve 25. When the second cylinder 28 is completely filled with the metal liquid materials, the second valve 25 is closed and the third valve 29 is opened. Next, the second piston 27 is lowered, causing the metal liquid materials to be transferred to the vaporizer 30 via the third valve 29. At this point, the first valve 21 is once again opened and the first piston 23 rises, causing the first cylinder 24 to again be filled with the metal liquid materials. As these processes are repeated, the metal liquid materials will be provided from the micropump 20 to the vaporizer 30. The control of the mass flow is determined by the cycle number of the stepping motors 22 and 26.
The metal liquid materials supplied from the micropump 20 will flow into 99 metal disks 32 via the delivery valve 31, and will be vaporized by heating zones 33 in the metal disks 32 and will then exit the vaporizer 30 along with the carrier gas.
The driving of the metal disks 32 in the vaporizer 30 depends on the metal liquid materials introduced therein. Furthermore, the micropump 20 and vaporizer 30 are arranged such that micropump can cause the formation of pressure in the vaporizer. Accordingly, it is extremely difficult to keep constant the pressure of the metal liquid materials and it takes a lot of time (several tens minutes) for the pressure of the metal liquid materials to attain an equilibrium state. In addition, at an initial state, if suction of the metal liquid materials occurs, a lot of metal liquid materials will be introduced into the metal disks 32. Thus, vaporization of the metal liquid materials is difficult and some of them will remain unvaporized, thereby clogging the vaporizer 30.
Accordingly, materials such as copper liquid materials have problems in that they are difficult to deposit uniformly on a wafer due to a very low vapor pressure and also because they decompose easily. And when they decompose in the metal disks, they are likely to cause clogging. Also, there is a problem in that they will degrade reproduction and thus will be impossible to apply for a mass production in the process of manufacturing a semiconductor device due to extremely short consecutive deposition periods.
It is therefore an object of the present invention to provide a liquid delivery system capable of not only improving the deposition speed of copper but also implementing reproduction thereof, when depositing a copper layer using copper liquid materials by means of a metal organic chemical vapor deposition method during the process of manufacturing a semiconductor device.
In order to accomplish the above object, the liquid delivery system (LDS) according to the present invention is characterized in that it comprises a vaporizer including:
a vaporizing chamber which has a second heating jacket provided at a side wall of said vaporizing chamber for vaporizing ultra-micro liquid drops of a copper liquid materials,
a heater provided at a bottom of said vaporizing chamber for vaporizing any ultra-micro liquid drops which were not vaporized, and
a pressure measuring apparatus, and a pressure pump having a throttle valve, for keeping the pressure in said vaporizing chamber to be constant;
a copper liquid materials supply apparatus including:
a canister filled with copper liquid materials,
a pressurized gas inlet line connected to said canister for introducing a pressurized gas into said canister, and
a copper liquid materials outlet line connected to said canister, and an orifice connected to a terminal end of said copper liquid materials outlet line, for supplying the copper liquid materials into said vaporizing chamber using the pressure from said pressurized gas inlet line;
a carrier gas supply apparatus including:
a first mass flow controller (MFC) for controlling the mass flow of a carrier gas,
a carrier gas outlet line having a first heating jacket, said carrier gas outlet line is connected to said first mass flow controller,
a jet nozzle connected to a terminal end of said carrier gas outlet line, for generating ultra-micro liquid drops by jetting the copper liquid materials passed through said orifice, and
an insulating block provided between said first heating jacket and said orifice for preventing a heat conduction, and
a sealing device provided at said nozzle section for maintaining vacuum of said vaporizing chamber; and
a jet system including:
a copper steam inlet line having a third heating jacket for keeping a copper steam vaporized at said vaporizing chamber,
a second mass flow controller (MFC) for controlling the mass flow of said copper steam and said carrier gas both of which are introduced from said copper steam inlet line, and
a copper steam outlet line connected to said second mass flow controller, and a copper steam jet connected to a terminal end of said copper steam outlet line, for jetting said copper steam into a reactive chamber.